Many types of optical proximity sensors are currently available. The design of such sensors will often depend upon the application in which the sensor is employed. Typical fields of application for optical proximity sensors include, without limitation, motion detection, controllers for computing devices (e.g., optical mouse, optical finger navigation, rollerball navigation, etc.), industrial applications, medical applications, transportation applications, computing applications, communications applications, aerospace applications, and so on.
As can be seen in FIG. 1, a typical optical proximity sensor 100 includes a substrate 104 upon which a light source 120 and a light detector 124 are mounted and housing 108 which provides a barrier between the light source 120 and light detector 124. The housing 108 may also serve a dual purpose of protecting the light source 120 and light detector 124 as well as other electronic components of the optical proximity sensor 100 from external forces.
In particular, the housing 108 may be designed to include a first module 112 and a second module 116. The first module 112 may include a top surface and four sidewalls which completely encapsulate or enclose the light source 120. Similarly, the second module 116 may include a top surface and four sidewalls which completely encapsulate or enclose the light detector 124. The sidewall of the first module 112 which is adjacent to the sidewall of the second module 116 may be referred to as the inner sidewall of each module 112, 116. In the embodiment depicted in FIG. 1, the inner sidewall of each module 112, 116 is used to form a u-bend feature 128 constructed of a folded material. The u-bend feature 128 serves two purposes. First, the u-bend feature 128 provides optical isolation between the light source 120 and light detector 124. Second, the u-bend feature 128 is a structural member which serves as an interface between the housing 108 and the substrate 104. More specifically, the u-bend feature 128 rests on the substrate 104 and is configured to convey vertical forces acting on the housing 108 laterally between modules 112, 116 as well as downwardly to the substrate 104. The u-bend feature 128 provides a mechanism for transferring and redirecting vertical forces imparted on the housing during fabrication or use.
Although not depicted in FIG. 1, the top surface of the first module 112 may comprise an aperture which allows light generated by the light source 120 to exit the housing 108 and reflect off of an object of interest. The top surface of the second module 116 may also comprise an aperture which allows light reflecting off of the object of interest (i.e., light originally emitted by the light source 120) to enter the cavity of the second module 116 and be detected by the light detector 124. The light detected by the light detector 124 may then be subsequently processed or analyzed according to the application in which the optical proximity sensor 100 is employed. In some instances, the light detected by the light detector 124 may be converted into x-y user-motion data that is subsequently converted into commands which control a pointer or cursor on a computational device's user interface.
As can be seen in FIG. 2, one issue which may arise with the optical proximity sensor 100 is that if the outer sidewalls 132, 136 of the modules 112, 116, respectively, (i.e., the sidewalls which oppose the inner sidewalls or u-bend feature 128) are not machined to fit snugly around the substrate 104, then the housing 108 may be prone to unwanted tilting. More specifically, if even a minor gap is present between one of the outer sidewalls 132, 136 and the outer edge of the substrate 104, then the u-bend feature 128 may act as a pivot point for the housing 108, which leads to unwanted tilting of the housing 108 with respect to the substrate 104. Minor gaps may occur even if the housing 108 and substrate 104 are within manufacturing tolerances. In particular, if the housing 108 is at the high end of its manufacturing tolerance and the substrate 104 is at the lowest end of its manufacturing tolerance, a gap is created which can allow even more tilt to occur.
Tilting of the housing 108 relative to the substrate 104 can have negative side effects including causing damage to the optical components 120, 124 of the optical proximity sensor 100 as well as leading to an unwanted shape and size of the optical proximity sensor 100. If the optical proximity sensor 100 is improperly sized or has an improper shape, the optical proximity sensor 100 may not be suitable for its intended application and may, therefore, be labeled as defective.
Other types of optical proximity sensors which are known in the art include, without limitation, those designed and manufactured by AVAGO TECHNOLOGIES™ such as HSDL-9100 surface-mount proximity sensors, APDS-9101 integrated reflective sensors, APDS-9120 integrated optical proximity sensors, APDS-9700, APDS-9800, etc.